1. Field of the Invention
Embodiments of the present invention relate to a vehicle running control apparatus configured to perform control regarding vehicle running in a vehicle, such as, for example, an automobile.
2. Description of the Related Art
For this type of apparatus, there is known an apparatus configured to automatically accelerate and decelerate a vehicle. Japanese Patent Application Laid Open No. 2009-173093 discloses that a process for gently decelerating a vehicle is performed if control is performed to stop the vehicle on a stop line, on an apparatus configured to assist a driver by determining, from lighting information regarding a traffic light, whether or not to pass through an intersection.
If the vehicle is automatically decelerated, a method of adjusting the deceleration of a self-vehicle with reference to a preceding vehicle can be used. Specifically, by changing the deceleration of the self-vehicle in accordance with an inter-vehicle distance and a relative speed to the preceding vehicle, it is possible to perform the deceleration while avoiding that the self-vehicle and the preceding vehicle excessively approach to or excessively separate from each other.
In the method based on the preceding vehicle described above, however, if the inter-vehicle distance or the relative speed to the preceding vehicle changes, the deceleration of the self-vehicle also changes at each time of the change. This possibly causes hunting in the deceleration of the self-vehicle depending on circumstances and may give the driver discomfort caused by unstable deceleration, which is technically problematic.